Monday, January 11, 2016

Mortality and Age

I spent some time recently picking through CDC’s mortality
data. My curiosity was piqued by recent reports of exploding mortality rates
due drug poisonings. Luckily you can download the data from CDC’s Wonder database
and cut it any way you like. Here’s what I found. Rates are given as deaths per
100k population. The CDC doesn’t have accurate population figures above age 85,
so I can’t get those mortality figures from the CDC. They are excluded from my
table. The CDC’s data query automatically calculates the mortality rate for you.
I’ve added three columns: the change in mortality at each age ( (final –
initial )/ initial), and the effect of one year of aging in both 2000 and 2014
(calculated as “this age’s mortality – prior age’s mortality”). So what does it
tell us?

(Table at bottom of post.)

Despite recent alarmism, I see mostly good news. The vast
majority of age groups (which you can get by each single year!) see a decline
in mortality over the past decade and a half. For eleven age groups, people age
25 – 35, mortality has actually increased. That’s not to say things look worse
if you’re a 30-year-old. Your life expectancy at age 30 isn’t just based on
your morality at age 30; it’s also based on mortality at all years *after* 30.
A randomly picked 30-year-old in 2000 could expect another 48.3 years of life (see here, page 25); a 30-year-old in 2013 could expect another 50.1 years of life ( see here, page 12). So this age category is not worse off than it was just over a decade
ago. The mortality at any given age is a small piece of the pie, since someone
is pretty unlikely to die in the 11 years that span 25 to 35. The improvement
in mortality at older ages makes up for the loss in that decade.

What really struck me was how mortality changes as you age.
When people talk about drug policy or gun policy, they’re talking about a few
points per 100k. If you believe the CDC’s figures, there are about 15 drug
poisonings per 100k. Gun homicides are significantly smaller. These magnitudes, while disturbingly high,
pale in comparison to the effect of aging even a few years. Aging from 30 to 35
increases your mortality by 31.9 points (deaths per 100k per year). Aging from 40 to 41
increases your mortality by 21.1 points.
It accelerates quickly from there. Aging from 50 to 51 increases your
mortality by 48.1 points (possibly that’s a mild outlier). Aging from 60 to 61
drives up mortality by 75.5 points.

Look at the improvements for ages 0 – 20. These are massive
improvements in our earliest years. The improved mortality at age 0, an age at
which mortality is famously quite high, is especially good news. People in
their mid-60s to mid-80s (where the CDC data stops) are also seeing some
impressive gains. All-cause mortality is dropping 20% or more for these ages. A
recent paper by Angus Deaton, 2015’s winner of the Economics Nobel, shows how a
few age and race demographics are seeing some losses (or at least failing to
realize the gains seen in other demographics). But the overall story is a
hopeful one. Relevant to my point, a critique I found of the Deaton paper points out that
the 44 – 54 age cohort has gotten older. The mortality effect of sheer aging
could explain some (not all) of the backsliding in this demographic
(specifically the non-Hispanic white 44-54 demographic).

If we fixate on middle years, age 30 – 60, the average
person was 43.6 in 2000 and 45.1 in 2014. Aging that year-and-a-half adds 34
points to your mortality (using 2014 mortality figures; obviously I have to
extrapolate a little for fractional years). For comparison, the largest single
cause of death in this age group in 2014 is ICD code C34.9, “Bronchus or lung,
unspecified – malignant neoplasms” (lung cancer, I presume), which comes in at
just under 20 deaths per 100k. A year and a half of aging has a larger
magnitude than any single cause of death. I don’t want to overstate my point;
admittedly the codes are pretty narrow, and the mortality for “all cancer” or
“all heart conditions” would probably be larger. And you may be saying, “No
crap. Older people die more.” Still, the magnitudes surprised me.

I don’t want to diminish the importance of social problems
like gun violence and drug overdoses. The rates are small, but the total
numbers of victims are in the tens of thousands, and each one is a tragedy. I’m
not advocating that we compare every problem to “one year of aging” and dismiss
it if it’s a lot smaller. Any particular policy approach to any particular
problem needs its own cost-benefit analysis. If there’s a problem that kills
only 10 people a year and it can be solved for, say, $100k, we shouldn’t
flippantly ignore the problem because of its smallness. We should spend the
money! And if a problem kills 100,000 people a year but doesn’t respond *at
all* to a multi-billion dollar “Just Do Something” government policy, we should
stop wasting our money. The overall magnitude of the problem is irrelevant to
the question of how to address it (or who should address it, or whether or not
to address it). If we simply ignored all problems smaller than “the effect of a
year of aging on mortality” we’d leave a lot of important, and more to the
point solvable, problems unsolved. Individual problems need to be understood
and addressed specifically and one-at-a-time, but we should certainly quantify
them and put them into perspective.